The aim of this study will be to determine and characterize the electrophysiological and morphological features of the mammalian gastric mucosa when damaged by such agents as hypertonic saline and alcohol. The rapid-repair process which follows any injury to the mucosa will be studied in some detail by electron microscopy and electrophysiology. The experiments will be made in Ussing chambers using stripped guinea pig and piglet gastric mucosa. The perfusion chambers will be monitored for electrical activity after exposure to damaging agents. Following injury the return of the electrophysiological parameters as well as the morphological restitutio of the epithelium will be characterized. The long-term aim of this study is to process and to evaluate whether fibronectin, epidermal growth factor, serum, or other substances may enhance the rapid repair process. Other agents or drugs or conditions which inhibit mucosal repair will also be investigated. This study involves basic disciplines in gastric physiology and morphology and is relevant to gastroenterology. A better understanding of what injures the gastric mucosa and how it is repaired is fundamental to our understanding of gastric ulcer formation and its cure.